A person who cannot for the life of them clear crumbs off their bed. So they sit on it, and flatten the crumbs out and until the crumbs keep collecting. Eventually Stay away from this person at all costs.

Danngg, that girl Mareyeen is a Crum bum, all she do is sit on her bed flattening crumbs.

The same kind of 'Fat cat'. Meaning a person became rich in wealth by leeching on poorers.
They are mostly White, Republican, and upper-middle age. The most infamous of all, Richard Bruce "Dick" Cheney, currently the Vice President of the United State of American(aka Advisor of Halliburton). Running our puppet President on a leash like his own personal bitch.

Jon Stewart of The Daily Show: Fat cats and Crumbums

Fat cat is slang term which describes a rich, greedy person who, due to ownership of large amounts of capital, is able to "live easy" off the work of others. Often, those labeled "fat cats" will reap a sustantial financial gain from a business, while the business itself, and the people who are employed by it, do not. The term is also sometimes used to refer disparagingly to wealthy contributors to a political campaign. The term stems off from the fact that since rich people can buy a lot of food, they both tend to resemble each other, the owner and the cat, in girth of waist, haughtiness, and a holier-than-thou attitude.